It was impossible to tell from his mien whether he was offended.

从他的面部表情无法判断他是否生气了。

《柯林斯英汉双解大词典》

On cloudy days or at night it was impossible to tell the time with a sun clock or a sundial.

在阴天或晚上，无法用太阳钟或日晷看出时间。

youdao

He also noted that because the coiffure was broken, it was impossible to tell whether the subject was a king or a god.

他也表示，因为发型已经被破坏，所以无法判断这个雕像究竟是一个国王，还是一位神。

youdao

It was impossible to tell whether he was there to spy for us or on us.

NPR: Sergeant Notes Odd Rituals of War in Afghanistan

Unlike other known political figures such as Sir Winston Churchill, she said, it was impossible to tell how popular the items would be.

BBC: Thatcher outfits to be sold at Christie's

Bill was a force of nature, and so it was impossible to tell whether his outburst was genuine or calculated drama, but it amounted to an earthquake.

NPR: Sergeant Notes Odd Rituals of War in Afghanistan